1. Field of the Invention
The present invention relates to a ratchet one-way clutch using ratchets (pawls) as a locking mechanism among one-way clutches used in a transmission for motor vehicles, farm machines, building machines, industrial machines and the like and having a back stop function, particularly a transmission for vehicles, and a stator for a torque converter using such a ratchet one-way clutch.
2. Related Background Art
In general, a one-way clutch used in an automatic transmission has outer and inner races which are rotated relative to each other, and sprags or rollers for transmitting torque between the outer race and the inner race are engaged by a track surface of the outer race or the inner race so that rotational torque is transmitted only in one direction. Further, the clutch is idly rotated in an opposite direction.
Among such one-way clutches, there is a ratchet one-way clutch in which a ratchet is used as a torque transmitting member for transmitting torque between the outer race and the inner race. The ratchet one-way clutch is constituted by an outer race provided at its inner periphery with pockets, an inner race disposed in coaxial with the outer race and provided at its outer periphery with notches, pawl members disposed within the pockets and adapted to be fitted into the notches of the inner race to establish a lock-up condition of the one-way clutch in which torque can be transmitted between the inner race and the outer race, and elastic members for biasing the pawl members towards the inner race.
In the ratchet one-way clutch having the above-mentioned arrangement, when the one-way clutch is rotated in one direction, since the pawl members are slid freely with respect to an outer periphery of the inner race, the outer race and the inner race are rotated idly relative to each other. If the one-way clutch tries to rotate in an opposite direction, the pawl members are fitted into the notches, thereby establishing the lock-up condition of the one-way clutch.
In recent years, development regarding compactness, light-weighting and cost reduction of parts of a motor vehicle such as a transmission has widely been effected, and the one-way clutch is also included in such interest. In order to meet such request, use of the ratchet one-way clutch has been proposed.
Generally, in the ratchet one-way clutch, the pawl members are contained in the pockets formed in the inner race or the outer race and are rocked around their gravity centers within the pockets. The pawls are engaged by recessed portions formed in the outer race or the inner race by such rocking movement, thereby transmitting the torque. Further, in order to facilitate the engagement between the pawl member and the recessed portion, each pawl member is biased toward the recessed portion by a biasing member.
Normally, since the pawl member within the pocket has relatively great clearances at both sides in an axial direction, the pawl may be shaken within the pocket after assembling or the assembling operation itself may become difficult. Further, due to the presence of such clearances, during the operation of the ratchet one-way clutch, movement of the pawl member may become unstable and thus the operation of the ratchet one-way clutch itself may become unstable. That is to say, the holding ability and operation reliability of the pawl member are not always satisfied.
Further, although the pawl member is biased by the biasing member, since a coil spring is normally used as the biasing member, positioning of the biasing member in a second pocket is apt to become unstable. Thus, there may be dispersion in an urging force against the pawl member, thereby affecting a bad influence upon the operation of the ratchet one-way clutch.
Accordingly, an object of the present invention is to provide a ratchet one-way clutch which can suppress shaking of parts and facilitate assembling and in which stability of an operating pawl can be achieved.
To achieve the above object, the present invention provides a ratchet one-way clutch comprising inner and outer races disposed on a same axis and in which a pawl member as a torque transmitting member and a biasing member for biasing the pawl member are provided in one of the inner and outer races and a recessed portion into which the pawl member is fitted is provided in the other of the inner and outer races so that torque can be transmitted by engagement between the pawl member and the recessed portion and wherein a first pocket for housing the pawl member is provided in either the outer race or the inner race, and a supporting portion for supporting the pawl member in an axial direction is provided on an inner surface of the first pocket.
In the present invention, since the first pocket for housing the pawl member is provided in either the outer race or the inner race and the supporting portion for supporting the pawl member in the axial direction is provided on the inner surface of the first pocket, operating stability of the pawl member can be achieved. Further, an assembling ability is enhanced and shaking of parts can be prevented.
Further, since there is provided a second pocket provided in wither the outer race or the inner race and communicated with the first pocket and adapted to contain a biasing means and the second pocket is provided with a stepped portion for positioning the biasing member, a biasing force against the pawl member becomes stable.